The herpes family of viruses can have a surprising upside — it can protect against the bubonic plague and other bacterial contagions, at least in mice.

Research into whether a similar mechanism applies to humans and other mammalian hosts should be conducted, said viral immunologist Skip Virgin at Washington University School of Medicine in St. Louis. "There may be symbiotic advantages to chronic infections with these viruses."

These new results do not mean people should go out and get infected with herpes, Virgin stressed. They probably already are.